1. Field of the Invention
This invention relates to the field of footwear, and in particular to a hard shell molded ski boot formed in two interfitting shell members.
2. Description of the Prior Art
A downhill ski boot is intended to make the user's foot and lower leg rigidly attachable to a ski. Steering motions of the user's lower leg, primarily consisting of tilting movements from side to side over the ski, must be fully and precisely transmitted to the ski for the most complete possible control. Tilting motions forward and backward over the ski are less important for steering, but have other effects. Fatigue can also be reduced by use of a boot which provides some support in the forward-bckward directions, allowing the user to assume a comfortable position, for example, leaning forward slightly.
It will be appreciated that to convey a certain side-to-side tilting movement precisely, the structure attaching the ski to the user's lower leg must be substantially rigid in the side-to-side plane. The prior art includes a number of ski boots adapted to attach a user's leg and ski, using a hard sole-block fixed to a relatively high point on the user's shin, by means of a rigid or only slightly resilient connecting structure.
Ski boots having hard molded plastic shells have been popular for some years. Such boots allow a relatively rigid connection between the wearer and the ski, usually via a sole-block molded monolithically with an upwardly extending portion on the front or rear of the boot. The extending portion encloses the user's lower leg. Often, the upward extension is adapted to pivot forward and backward with respect to the ski, around an axis passing horizontally through the user's ankle, the axis being transverse to the direction of travel. Such pivoting causes the side-to-side tilting motions of the user to be directly transmitted to the ski, but permits the user to lean forward and backward over the ski freely. Adjustable spring biasing means to set the extent to which the user can freely lean forward and backward are also known in connection with such pivoting ski boots.
In order to affix a user's leg to a boot tightly, and especially to a hard plastic shell boot, the art teaches several alternative procedures. In some boot designs, surface members have flaps which, although themselves stiff, may be adjustably brought together or slid across one another to reduce the circumference of a part of the boot enclosing the user's foot or leg. This approach is much like the traditional means of tightening footwear, namely flaps which are brought together by means of laces, in order to adjust the circumference of a part of the shoe or boot member enclosing the user's foot and/or leg.
A formerly popular method of attaching a molded boot having a hard plastic shell to a user's foot involved molding a custom inner boot to the exact contour of the user's foot, and enclosing the custom molded inner member in a hard outer shell of standard dimensions. The inner boot was molded in situ, that is, using the user's foot and leg for a part of the mold form. The exact contours of any user's foot could thereby be encompassed by a standard sized hard plastic boot shell. The custom molded inner member was formed of insulating material, and was at least semi-rigid for support.
Currently-popular custom boots employ foam pads within hard shell outer boots. Such an approach is similar to the use of a custom-molded inner boot in that the resilient insulating material may be correctly sized for precise fit. Unlike custom molding, no special molding equipment or curable pre-cursor foam material need be used.
Although custom boots, however, made, may fit absolutely perfectly when made, the boots cannot account for typical variations in the size of a given user's foot over time. In addition, the semi-rigid lining material which was originally fit to the user's foot, tends to become worn and crushed by the user's motions in walking and skiing, gradually enlarging the space allowed for the user's foot. Therefore, the prior art also teaches means for adjustably tightening the fit of even custom fitted boots.
Known tightening means include a bale or pivotable loop adapted to fit into any of a series of spaced hooks, an adjustable pressure plate for pressing against the user's instep, and belt members extending through the boot and connected to an external adjustment means. With use the boot wears and the original precision of the custom fit is lost. Similarly, should the user's feet swell or shrink, the custom fitted pads no longer precisely fit the user's feet. In these situations, the adjustment device effectively becomes the basic means and support by which the user's foot is attached to the ski.
Inadequacies in fit are aggravated by closures or tighteners which can be set only at discrete intervals. The user may find that the boot is too tight at one position and too loose at the next. In any event, once the usual tightener is moved into an operative position at which the tightener contacts the user's foot, the precision of the original fit is of no consequence, because the tightener, not the overall boot, accomplishes the structural interconnection of user and ski.
The user must tighten the adjustment means to close the liner around his foot tightly enough at the adjustment point to make up for any inadequacies in fit caused by wear of the lining material. Such tightening further compresses the liner and further deteriorates the fit. Even given the various means for custom fitting the inner contour of the boot, and means for adjusting the pressure exerted at various points within the custom-molded boot, the user still finds that all too frequently, the boot is either too tight or too loose. If too loose, the user loses a measure of control over steering the skis, due to loss of full control over the precise tilt applied from side to side to the skis. Looseness also permits relative movement between the user and the boot, often abrading the user'leg, especially at the shin, adjacent to the boot top. If the adjustment means are too tight, the user will be not only uncomfortable, but may develop frostbite due to undue pressure and lack of circulation. Whether the boot is too tight or too loose, poor fit can cause blisters.
The tightness of the connection between the user and the boot (and therefore the ski) can help or hinder the user's safety. If boots are too loose, the skis are more difficult to steer around obstacles. Loose boots will not support the wearer's bones and joints well in falls, leading to more frequent breaks and strains. On the other hand, if the boots are too tight, the wearer's feet will become numb. Frostbite is a primary danger, but in addition, a user with numb feet will be less able to discern the condition of the skis, the precise snow surface, and other possibly subtle tactile clues. The optimum boot is, of course, one which conforms identically to the user's foot with every wearing. The boot is loose enough for comfort and circulation and tight enough to convey directly leg movements to the ski and prevent chafing between the user and the boot.
The present invention provides a means by which the user's foot and lower leg are custom fitted to the bottom and back of the boot each and every time the boot is put on. The front cover member of the boot fits integrally into a series of recesses providing structural attachment with the rear member, closing the boot to snow and moisture, and providing additional structural support and rigidity. Interchangeable front covers allow the user to choose from a range of support parameters. The front cover shell does not close tightly against the user's leg, which might possibly obstruct blood circulation. The bottom and back-mounted adjustment means is continuously-adjustable, rather than adjustable only to one of a series of discrete positions, preferably using attachment belts having loop and pile fasteners. The attachment belts are affixed to the inner surfaces of the boot at spaced points, further securing the user's foot and leg to the bottom and rear of the boot.